Apex domains cannot have CNAME records.
Question and response
Question
dig gg. NS
Answer
gg. 5 NS e.ci-servers.net.
gg. 5 NS dns4.nominetdns.uk.
gg. 5 NS dns2.nominetdns.uk.
gg. 5 NS dns3.nominetdns.uk.
gg. 5 NS c.ci-servers.org.
gg. 5 NS dns1.nominetdns.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0